Respiratory Physiology 2

Question 1

What is the definition of dalton’s law?

Answer 1

How gases move down their concentration gradient by diffusion

Question 2

What is the definition of Henry’s law?

Answer 2

How the solubility of a gas relates to its diffusion

Question 3

Internal respiration

Answer 3

Oxygenated blood turns into deoxygenated blood as O2 and CO2 move down their partial pressure gradients- either back into blood or into tissue

Question 4

Each haemoglobin molecule transports how many oxygen molecules?

Answer 4

4 O2 molecules

Question 5

What does oxygen level measure?

Answer 5

Amount of oxygen dissolved in the plasma

Question 6

What is haemoglobin’s structure?

Answer 6

4 polypeptide chains: 2 alpha and 2 beta

4 haem groups ( 1 bound to each polypeptide chain)

Question 7

What is the structure of the haem group?

Answer 7

Porphyryn ring with an iron ion in the centre

Question 8

Each iron ion in haem group binds to howmany molecules of o2?

Answer 8

1- can bind to molecule of oxygen in a reversible manner

Question 9

Why is the Saturation of Hb-O2 and partial pressure graph of oxygen sigmoidal?

Answer 9

Difficult for first molecule to bind to haem group
Conformational change, make easier for rest to bind
Full saturation hard to achieve because only one haem group left for fourth molecule of O2, harder for O2 to find it

Question 10

How is most oxygen transported?

Answer 10

Being bound to Hb

Question 11

What is the Bohr Effect?

Answer 11

In tissues that need more O2, the local environment moves hB-O2 curve to the right aiding unloading of O 2

Question 12

What factors cause the sigmoidal curve to move to the left?

Answer 12

Low CO2 concentration environments
High pH concentrations
Fetal blood- higher affinity for o2 than mother

Question 13

What does partial pressure of O2 measure?

Answer 13

Dissolved oxygen not oxygen carried by Hb

So pp of O2 in blood is the same even if amount of haemoglobin decreased to half=anaemia

Question 14

How is CO2 carried in the blood? (3 ways)

Answer 14

Dissolved in plasma
Bicarbonate (H2CO3 which dissociates to H+ and HCO3-)= main one
Carbamino compounds

Question 15

Method of how CO2 gets into blood

Answer 15

CO2 enters blood
High levels of carbonic anhydrase catalysing the reaction between CO2 and water to carbonic acid
Carbonic acid dissociates to hydrogen carbonate ions and hydrogen ions.
Hydrogen carbonate ions move out of erythrocyte into plasma via diffusion
Negatively charged chloride ions move in to maintain electrical balance of cells=chloride shift

Question 16

How Co2 leaves blood at lungs

Answer 16

Low conc of CO2
Carbonic anhydrase catalyses reverse reaction breaking down carbonic anhydrase to CO2 and H20
Carbonic anhydrase diffuse back into erythrocyte react with H+ to form carbonic acid then broken down to produce CO2 and H20. Co2 diffuse out of blood into lungs

Question 17

What acts as a buffer in blood?

Answer 17

Haemoglobin will bind with the H+ to form haemoglobinic acid from the dissocation of carbonic acid and from dissociation of carbaminohaemoglobin that forms H+ and carbamino group

Question 18

How does the amount of CO2 in the blood affect the amount of O2 in blood?

Answer 18

The more CO2 there is the less O2 that can be carried.

HbO2 + H+ lead to HbH+ + O2

Question 19

What is the Haldane effect?

Answer 19

CO2 loading/unloading enhanced by O2 unloading/loading respectively

Question 20

How do baroreceptors play a part in respiration? Where are they located?

Answer 20

Stimulate respiration in response to hypotension (aortic and carotid bodies)

Question 21

Signals are send from the respiratory centre in the medulla to the muscles involved in breathing through which nerves?

Answer 21

Phrenic and intercostal nerves

Question 22

How do chemoreceptors play a part in respiration? Where are they?

Answer 22

Respond to decreases in oxygen and metabolic acidosis, also responds to changes in pH of cerebrospinal fluid

Question 23

How do mechanoreceptors play a part in respiration?Where are they?

Answer 23

Stimulate respiration in response to exercise- in muscles/joints